Brass, a copper-zinc-base alloy, possesses excellent workability, strength, and corrosion resistance and thus is used in various applications. Under some use conditions, however, dezincification corrosion sometimes occurs in which zinc, a constituent element of the alloy, is eluted prior to copper and other ingredients. This tendency increases with an increase in zinc content. It is known that, in brass including copper and zinc at a copper:zinc content ratio of about 60:40, a two-phase structure of α phase and zinc-rich β phase is formed and dezincification corrosion selectively occurs in the β phase.
As means for preventing dezincification corrosion, Sn (tin), P (phosphorus) and the like are added and heat treatment is carried out. Alloys of which corrosion resistance has been improved by this method, i.e., by removing the β phase from the two-phase structure after casting or hot working to form a single-phase structure of an α phase, or by minimizing the proportion of the β phase are placed on the market as a dezincification-resistant brass.
However, the heat treatment for obtaining the dezincification-resistant brass is a complicated heat treatment step, and the brass obtained by this process the cost which is higher than that of ordinary brass. Further, when the dezincification-resistant brass is cast or forged, heat treatment should be carried out after the working, resulting in significantly lowered productivity.